MiniPrototype CosmicRuns
Cosmic Coincidences
setup
Setup a cosmic coincidence experiment with two crossed scintillators that have the proto-type drift chambers sandwhiched between them.
Built 4 100 ns long delay cables. 2 for the PMTs and one for sense wire 7 on each of the drift chambers.
The top PMT is in channel 7 of the QDC and channel 16 of the scaler.
The Bottom PMT is on channel 8 of the QDC and channel 7 of the scaler.
Coincidence counts are recorded in channel 2 of the scaler.
Runs
Drift Chamber is off
Run 182: Ran with coincidence module in "OR" mode so if either paddle triggered the ADC was read out
Run 183: Switched coincidence module to "AND" mode and ran overnight.
12/23/07
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | 19 |
| Field | -800 | 19 |
| Guard | 800 | 0 |
Run 204: Scope was plugged into DC output (split signal)
12/24/07
Run 206: Unplugged scope and started this run
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | 19 |
| Field | -800 | 19 |
| Guard | 800 | 0 |
I had a bad ribbon cable on plastica. Ignore the results for Plastica. It was just a good pedestal measurement.
It looks like Metalica saw 2/3 of the cosmics seen by the Scintilaltors.
12/27/07
Run 207:
Scope picture of a Cosmic Coincidence event triggered by and AND between the top and bottom scintillator.
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | |
| Field | -800 | |
| Guard | 800 | |
Metalica saw 488 cosmic events while Plastica recorded 494 out of the 739 cosmic events triggered by the scintillator paddles. Assuming counting statistics, I would conclude that the efficiency of Metalica is and for Plastica when the scintillator paddle is 0.5 cm from the endplate.
12/28/07
Run 208:
Increased Gate width from 200 ns to 800 ns after realizing that the drift chamber pulses could be that wide. I also removed the 100 ns decay line on sense wire #4 of both chambers. The PMT pulses still have a 100 ns delay line in.
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1500 | |
| Field | -800 | |
| Guard | 800 | |
I saw the ADC peak move up from channel 200 to channel 500 after increasing the gate width.
Metalica saw 922 cosmic events while Plastica recorded 927 out of the 1361 cosmic events triggered by the scintillator paddles. Assuming counting statistics, I would conclude that the efficiency of Metalica is and for Plastica when the scintillator paddle is 0.5 cm from the endplate.
12/28/07
Run 209:
I increase the HV on both Drift chamber by 50 Volts (25 Volts on guard and Field wires).
Drift Chamber turned on with 90/10 ArCO2 and the voltages below
| HV settings | ||
| Wire | Volts | current (A) |
| Sense | 1550 | 94 |
| Field | -825 | 93 |
| Guard | 825 | 0 |
The GAS bottle is geting low!